An Auckland GP convicted of possessing images of child abuse is among the criminal medical professionals allowed to keep working.

Nineteen medical professionals with criminal convictions have appeared before the Health Practitioners Disciplinary Tribunal in the past three years, with eight struck off. Offences included grooming children for sex, assaulting a police officer, fraud and drug dealing.

A child advocate says the decision to allow two doctors to keep working despite being caught with images of child abuse raises serious questions about the tribunal. "They should have been struck off," Stop Demand founder Denise Ritchie said. "These men have a sexual interest in children."

Parents would be horrified to learn their family doctor had masturbated to images of young girls, she said.

The Auckland GP was granted permanent name suppression after being sentenced to four months' home detention and being suspended from work for nine months. He now works at an Auckland clinic and listed his expertise as child health and obstetrics.

He was caught with 290,000 images of pornography featuring young girls, and is now on medication to reduce his pornography addiction. Conditions around continuing to practise include counselling and mentoring. However, a psychiatric report raised concerns that his criminal urges might return if he stopped taking his medication.

"There does remain an inevitable question mark over whether Dr Y will escape from this addiction," the tribunal noted.

The doctor and clinic refused to comment.

Ritchie said the name suppression ruling added to the shroud of secrecy protecting doctors.

The tribunal has charged 50 medical professionals with professional misconduct due to criminal convictions since 2004.

In the past three years, six nurses, one X-ray technologist and a pharmacist were struck off the medical register for convictions ranging from theft to sexual misconduct. In the same period, 10 criminal medical professionals kept their practising certificate, including the two doctors caught with child pornography.

A second medical professional, Dr Andrew Jeremy Dunkley, was suspended for nine months after being caught with 50,000 pornographic images of teenage girls. As part of his conditions he must have a chaperone when treating females under 18 for three years.

In 2009, two nurses convicted separately of downloading images of child abuse were struck off the register. Medical professionals struck off are able to reapply for registration.

In August, Justice Minister Judith Collins proposed tougher penalties to curb the "terrible abuse suffered by children" used in pornographic images but the Government has no jurisdiction over the Health Practitioners Disciplinary Tribunal.

Collins said it was never appropriate for any child to be put in a situation where they might be at risk of serious harm. "I'd hope the tribunal respects the views of the community and the rights of children to be safe from harm when making decisions about practitioners who have been convicted of serious crimes."

Gary Fraser, the tribunal's senior executive officer, said public safety was the number one concern, but "there are a number of other things [the tribunal] do need to take into consideration, like issues around rehabilitation."

Patients did not have to be informed of a doctor's past convictions but decisions were kept on the tribunal's website.

"There are some practitioners, of course, who have permanent name suppression but not many."

Often the tribunal granted name suppression when a court order already existed.

Law professor Ron Paterson exposed flaws within the medical disciplinary system in his book The Good Doctor.

It highlighted a reluctance of doctors to judge other doctors who had committed crimes, with the approach being to have a "quiet chat" to solve issues.

Paterson contrasted that approach with nurses, who traditionally take a harder line on disciplinary matters.

AUT University researcher Kate Diesfeld, who specialises in tribunal law, said nurses were tougher on themselves than doctors.

She said she recalled a complaint about a nurse stealing a banana and yoghurt, but she doubted a doctor would be reported for the same incident. "Nurses are more stringent and vigilant about the profession's reputation and public safety."

It is not the first time convictions of medical professionals have caused controversy.

In 2000 disgraced Canterbury GP Morgan Fahey was sentenced to six years' jail for rape and sexual violation between 1966 and 1997.

His crimes sparked an external report to the Medical Council which found doctors who sexually offended were generally male GPs, middle-aged and eminent.